Oysters Rockefeller

Ingredients

• 1/4 cup panko breadcrumbs
• Extra-virgin olive oil
• 12 medium, sweet and briny oysters, such as Kumamoto
• 1/4 cup Double-Creamed Spinach, recipe follows
• 3 slices bacon, cut into 1 1/2-inch pieces
• Coarse salt, for baking sheet
• Fennel pollen, for garnish
• Fresh horseradish, grated, optional
• Smoked olive oil, optional
• 3 lemons, cut into wedges
• 3/4 pound fresh spinach, cleaned
• Kosher salt and freshly ground black pepper
• 1/2 fennel bulb
• 1/2 large onion
• 3/4 teaspoon extra-virgin olive oil
• 1 clove garlic, minced
• 1 1/2 tablespoons flour
• 2 tablespoons Herbsaint
• 1/2 cup whole milk
• 1 tablespoon butter
• 1/4 teaspoon grated nutmeg
• 2 to 3 tablespoons freshly grated Parmesan